Apparatus for thermal-slide debonding of temporary bonded semiconductor wafers

ABSTRACT

A debonder apparatus for debonding two via an adhesive layer temporary bonded wafers includes a top chuck assembly, a bottom chuck assembly, a static gantry supporting the top chuck assembly, an X-axis carriage drive supporting the bottom chuck assembly, and an X-axis drive control. The top chuck assembly includes a heater and a wafer holder. The X-axis drive control drives horizontally the bottom chuck assembly from a loading zone to a process zone under the top chuck assembly and from the process zone back to the loading zone. A wafer pair comprising a carrier wafer bonded to a device wafer via an adhesive layer is placed upon the bottom chuck assembly at the loading zone oriented so that the unbonded surface of the device wafer is in contact with the bottom assembly and is carried by the X-axis carriage drive to the process zone under the top chuck assembly and the unbonded surface of the carrier wafer is placed in contact with the top chuck assembly. The X-axis drive control initiates horizontal motion of the X-axis carriage drive along the X-axis while heat is applied to the carrier wafer via the heater and while the carrier wafer is held by the top chuck assembly via the wafer holder and thereby causes the device wafer to separate and slide away from the carrier wafer.

CROSS REFERENCE TO RELATED CO-PENDING APPLICATIONS

This application claims the benefit of U.S. provisional application Ser.No. 61/169,753 filed Apr. 16, 2009 and entitled “IMPROVED APPARATUS FORTEMPORARY WAFER BONDING”, the contents of which are expresslyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an apparatus for thermal-slidedebonding of temporary bonded semiconductor wafers, and moreparticularly to an industrial-scale thermal-slide debonder for debondingsemiconductor wafers bonded via an adhesive.

BACKGROUND OF THE INVENTION

Several semiconductor wafer processes include wafer thinning steps. Insome applications the wafers are thinned down to a thickness of lessthan 100 micrometers for the fabrication of integrated circuit (IC)devices. Thin wafers have the advantages of improved heat removal andbetter electrical operation of the fabricated IC devices. In oneexample, GaAs wafers are thinned down to 25 micrometers to fabricatepower CMOS devices with improved heat removal. Wafer thinning alsocontributes to a reduction of the device capacitance and to an increaseof its impedance, both of which result in an overall size reduction ofthe fabricated device. In other applications, wafer thinning is used for3D-Integration bonding and for fabricating through wafer vias.

Wafer thinning is usually performed via back-grinding and/or chemicalmechanical polishing (CMP). CMP involves bringing the wafer surface intocontact with a hard and flat rotating horizontal platter in the presenceof a liquid slurry. The slurry usually contains abrasive powders, suchas diamond or silicon carbide, along with chemical etchants such asammonia, fluoride, or combinations thereof. The abrasives causesubstrate thinning, while the etchants polish the substrate surface atthe submicron level. The wafer is maintained in contact with theabrasives until a certain amount of substrate has been removed in orderto achieve a targeted thickness.

For wafer thicknesses of over 200 micrometers, the wafer is usually heldin place with a fixture that utilizes a vacuum chuck or some other meansof mechanical attachment. However, for wafer thicknesses of less than200 micrometer and especially for wafers of less than 100 micrometers,it becomes increasingly difficult to mechanically hold the wafers and tomaintain control of the planarity and integrity of the wafers duringthinning. In these cases, it is actually common for wafers to developmicrofractures and to break during CMP.

An alternative to mechanical holding of the wafers during thinninginvolves attaching a first surface of the device wafer (i.e., waferprocessed into a device) onto a carrier wafer and thinning down theexposed opposite device wafer surface. The bond between the carrierwafer and the device wafer is temporary and is removed upon completionof the thinning and any other processing steps.

Several temporary bonding techniques have been suggested including usingof adhesive compounds or using of adhesive tapes or layers. Thinneddevice wafers are debonded from the carrier wafers after processing bychemically dissolving the adhesive layer or by applying heat orradiation in order to decompose the adhesive layer or tape. Extreme careis needed during the debonding process in order to avoid fracture,surface damage, or warping of the extremely thin wafers, typicallyhaving a thickness of about 2-80 micrometers. It is desirable to providean industrial-scale apparatus for debonding adhesively bondedsemiconductor wafers that protects extremely thinned wafers fromfracture, surface damage or warping.

SUMMARY OF THE INVENTION

In general, in one aspect, the invention features a debonder apparatusfor debonding two via an adhesive layer temporary bonded wafersincluding a top chuck assembly, a bottom chuck assembly, a static gantrysupporting the top chuck assembly, an X-axis carriage drive supportingthe bottom chuck assembly, and an X-axis drive control. The top chuckassembly includes a heater and a wafer holder. The X-axis drive controldrives horizontally the bottom chuck assembly from a loading zone to aprocess zone under the top chuck assembly and from the process zone backto the loading zone. A wafer pair comprising a carrier wafer bonded to adevice wafer via an adhesive layer is placed upon the bottom chuckassembly at the loading zone oriented so that the unbonded surface ofthe device wafer is in contact with the bottom assembly and is carriedby the X-axis carriage drive to the process zone under the top chuckassembly and the unbonded surface of the carrier wafer is placed incontact with the top chuck assembly. The X-axis drive control initiateshorizontal motion of the X-axis carriage drive along the X-axis whileheat is applied to the carrier wafer via the heater and while thecarrier wafer is held by the top chuck assembly via the wafer holder andthereby causes the device wafer to separate and slide away from thecarrier wafer.

Implementations of this aspect of the invention may include one or moreof the following features. The debonder further includes a lift pinassembly designed to raise and lower wafers placed on the bottom chuckassembly. The debonder further includes a base plate supporting theX-axis carriage drive and the static gantry. The base plate comprises ahoneycomb structure and vibration isolation supports or a granite plate.The bottom chuck assembly includes a bottom chuck comprising a lowthermal mass ceramic material and is designed to slide horizontallyalong the X-axis upon the X-axis carriage drive and to twist around theZ-axis. The X-axis carriage drive comprises an air bearing carriagedrive. The debonder further includes two parallel lateral carriageguidance tracks guiding the X-axis carriage drive in its horizontalmotion along the X-axis. The top chuck assembly further includes a topsupport chuck bolted to the static gantry, a heater support plate incontact with the bottom surface of the top support chuck, the heaterbeing in contact with the bottom surface of the heater support plate, atop wafer plate in contact with the heater, a Z-axis drive for movingthe top wafer plate in the Z-direction and placing the top wafer platein contact with the unbonded surface of the carrier wafer and a plateleveling system for leveling the top wafer plate and for providing wedgeerror compensation of the top wafer plate. The wafer holder may bevacuum pulling the carrier wafer. The plate leveling system comprisesthree guide shafts connecting the heater to the top support chuck andthree pneumatically actuated split clamps. The heater comprises twoindependently controlled concentric heating zones configured to heatwafers having a diameter of 200 or 300 millimeters, respectively.

In general, in another aspect, the invention features a method fordebonding two via an adhesive layer temporary bonded wafers, includingthe following steps. First, providing a bonder comprising a top chuckassembly, a bottom chuck assembly, a static gantry supporting the topchuck assembly, an X-axis carriage drive supporting the bottom chuckassembly and an X-axis drive control configured to drive horizontallythe X-axis carriage drive and the bottom chuck assembly from a loadingzone to a process zone under the top chuck assembly and from the processzone back to the loading zone. Next, loading a wafer pair comprising acarrier wafer bonded to a device wafer via an adhesive layer upon thebottom chuck assembly at the loading zone oriented so that the unbondedsurface of the device wafer is in contact with the bottom assembly.Next, driving the X-axis carriage drive and the bottom chuck assembly tothe process zone under the top chuck assembly. Next, placing theunbonded surface of the carrier wafer in contact with the top chuckassembly and holding the carrier wafer by the top chuck assembly. Next,heating the carrier wafer with a heater comprised in the top chuckassembly. Finally, initiating horizontal motion of the X-axis carriagedrive along the X-axis by the X-axis drive control while heat is appliedto the carrier wafer and while the carrier wafer is held by the topchuck assembly and thereby causing the device wafer to separate andslide away from the carrier wafer.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and description below. Other features, objectsand advantages of the invention will be apparent from the followingdescription of the preferred embodiments, the drawings and from theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the figures, wherein like numerals represent like partsthroughout the several views:

FIG. 1 is an overview schematic diagram of the improved temporary waferbonder and debonder system according to this invention;

FIG. 1A is a schematic diagram of temporary wafer bonding process A anddebonding process A performed in bonder module A and debonder A of FIG.1, respectively;

FIG. 1B depicts a schematic cross-sectional view of the bonder module Aof FIG. 1 and a list of the process steps for performing the temporarywafer bonding process A of FIG. 1A;

FIG. 2A is a schematic diagram of temporary wafer bonding process B anddebonding process B performed in bonder module B and debonder B of FIG.1, respectively;

FIG. 2B depicts a schematic cross-sectional view of the bonder module Bof FIG. 1 and a list of the process steps for performing the temporarywafer bonding process B of FIG. 2A;

FIG. 3A is a schematic diagram of temporary wafer bonding process C anddebonding process C performed in bonder module C and debonder C of FIG.1, respectively;

FIG. 3B depicts a schematic cross-sectional view of the bonder module Cof FIG. 1, and a list of the process steps for performing the temporarywafer bonding process C of FIG. 3A;

FIG. 4 depicts a view of a fixture chuck;

FIG. 5 depicts the temporary wafer bonder cluster of FIG. 1;

FIG. 6 depicts a closer view of the upper structure of the temporarywafer bonder cluster of FIG. 5;

FIG. 7 depicts a cross-sectional view of the upper structure of thetemporary wafer bonder cluster of FIG. 5;

FIG. 8 depicts the hot plate module of the temporary wafer bondercluster of FIG. 7;

FIG. 9 depicts a temporary bond module of the wafer bonder cluster ofFIG. 7;

FIG. 10 depicts a schematic cross-sectional diagram of the temporarybonder module of FIG. 9;

FIG. 11 depicts a cross-sectional view of the temporary wafer bondermodule of FIG. 9 perpendicular to the load direction;

FIG. 12 depicts a cross-sectional view of the temporary wafer bondermodule of FIG. 9 in line with the load direction;

FIG. 13 depicts the top chuck leveling adjustment in the temporary waferbonder module of FIG. 9;

FIG. 14 depicts a cross-sectional view of the top chuck of the temporarywafer bonder module of FIG. 9;

FIG. 15 depicts a detailed cross-sectional view of the temporary waferbonder module of FIG. 9;

FIG. 16 depicts a wafer centering device with the pre-alignment arms inthe open position;

FIG. 17 depicts wafer centering device of FIG. 16 with the pre-alignmentarms in the closed position;

FIG. 18A depicts the pre-alignment of a 300 mm wafer;

FIG. 18B depicts the pre-alignment of a 200 mm wafer;

FIG. 19A depicts another wafer centering device for the pre-alignment ofa 300 mm wafer;

FIG. 19B depicts the wafer centering device of FIG. 19A for thepre-alignment of a 200 mm wafer;

FIG. 19C depicts another wafer centering device for the pre-alignment ofa wafer with the rotating arms in the open position;

FIG. 19D depicts the wafer centering device of FIG. 19C with therotating arms in the closed position;

FIG. 20A, FIG. 20B and FIG. 20C depict the loading of the non-adhesivesubstrate and its transfer to the upper chuck;

FIG. 21A, FIG. 21B and FIG. 21C depict the loading of the adhesivesubstrate and its transfer to the lower chuck;

FIG. 22A and FIG. 22B depict bringing the adhesive substrate in contactwith the non-adhesive substrate and the formation of a temporary bondbetween the two substrates;

FIG. 23 depicts an overview diagram of the thermal slide debonder A ofFIG. 1;

FIG. 24 depicts a cross-sectional view of the top chuck assembly of thedebonder A of FIG. 23;

FIG. 25 depicts a cross-sectional side view of the debonder A of FIG.23;

FIG. 26A, FIG. 26B and FIG. 26C depict the thermal slide debonder Aoperational steps;

FIG. 27 depicts an overview diagram of the mechanical debonder B of FIG.1;

FIG. 28 depicts a cross-sectional side view of the debonder B of FIG.27; and

FIG. 29 depicts the debonder B operational steps.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, an improved apparatus for temporary wafer bondingand debonding 100 includes a temporary bonder cluster 110 and a debondercluster 120. The temporary bonder cluster 110 includes temporary bondermodule A, module B, module C, and module D, 210, 310, 410 and 510respectively. Debonder cluster 120 includes a thermal slide debonder A150, a mechanical debonder B 250 and a radiation/mechanical debonder C350. Bonder cluster 110 facilitates the temporary bonding processes A,B, C, and D, 60 a, 70 a, 80 a and 90 a, shown in FIG. 1A, FIG. 2A, FIG.3A, and FIG. 4, respectively, among others. Debonder cluster 120facilitates the debonding processes A, B and C, 60 b, 70 b, and 80 b,shown in FIG. 1A, FIG. 2A and FIG. 3A, respectively.

Referring to FIG. 1A, temporary bond process A 60 a includes thefollowing steps. First, device wafer 20 is coated with a protectivecoating 21 (62), the coating is then baked and chilled (63) and then thewafer is flipped (64). A carrier wafer 30 is coated with an adhesivelayer 31 (65) and then the coating is baked and chilled (66). In otherembodiments, a dry adhesive film is laminated onto the carrier wafer,instead of coating an adhesive layer. Next, the flipped device wafer 20is aligned with the carrier wafer 30 so that the surface of the devicewafer with the protective coating 20 a is opposite to the surface of thecarrier wafer with the adhesive layer 30 a (67) and then the two wafersare bonded (68) in temporary bonder module A, shown in FIG. 1B. The bondis a temporary bond between the protective layer 21 and the adhesivelayer 31. In other embodiments, no protective coating is applied ontothe device wafer surface and the device wafer surface 20 a is directlybonded with the adhesive layer 31. Examples of device wafers includeGaAs wafers, silicon wafers, or any other semiconductor wafer that needsto be thinned down to less than 100 micrometers. These thin wafers areused in military and telecommunication applications for the fabricationof power amplifiers or other power devices where good heat removal andsmall power factor are desirable. The carrier wafer is usually made of anon-contaminating material that is thermally matched with the devicewafer, i.e., has the same coefficient of thermal expansion (CTE).Examples of carrier wafer materials include silicon, glass, sapphire,quartz or other semiconductor materials. The diameter of the carrierwafer is usually the same as or slightly larger than the diameter of thedevice wafer, in order to support the device wafer edge and preventcracking or chipping of the device wafer edge. In one example, thecarrier wafer thickness is about 1000 micrometers and the totalthickness variation (TTV) is 2-3 micrometers. Carrier wafers arerecycled and reused after they are debonded from the device wafer. Inone example, adhesive layer 31 is an organic adhesive WaferBOND™HT-10.10, manufactured by Brewer Science, Missouri, USA. Adhesive 31 isapplied via a spin-on process and has a thickness in the range of 9 to25 micrometers. The spin speed is in the rage of 1000 to 2500 rpm andthe spin time is between 3-60 second. After the spin-on application, theadhesive layer is baked for 2 min at a temperature between 100° C. to150° C. and then cured for 1-3 minutes at a temperature between 160° C.to 220° C. WaferBOND™ HT-10.10 layer is optically transparent and isstable up to 220° C. After the thinning of the exposed device wafersurface 20 b the carrier wafer 30 is debonded via the debond process A60 b, shown in FIG. 1A. Debond process A 60 b, includes the followingsteps. First heating the wafer stack 10 until the adhesive layer 31softens and the carrier wafer 30 slides off from the thinned wafer (69).The WaferBOND™ HT-10.10 debonding time is less than 5 minutes. Thethinned wafer 20 is then cleaned, any adhesive residue is stripped away(52) and the thinned wafer is placed in a dicing frame 25 (53) In someembodiments, a small rotational motion (twisting) of the carrier wafertakes place prior to the sliding translational motion.

The temporary bonding (68) of the carrier wafer 30 to the device wafer20 takes place in temporary bonder module A, 210. Referring to FIG. 1B,the device wafer 20 is placed in the fixture chuck 202 and the fixturechuck is loaded in the chamber 210. The carrier wafer 30 is placed withthe adhesive layer facing up directly on the bottom chuck 210 a and thetwo wafers 20, 30 are stacked and aligned. The top chuck 210 b islowered down onto the stacked wafers and a low force is applied. Thechamber is evacuated and the temperature is raised to 200° C. for theformation of the bond between the protective coating layer 21 and theadhesive layer 31. Next, the chamber is cooled and the fixture isunloaded.

The debond process A 60 b is a thermal slide debond process and includesthe following steps, shown in FIG. 1A. The bonded wafer stack 10 isheated causing the adhesive layer 31 to become soft. The carrier waferis then twisted around axis 169 and then slid off the wafer stack undercontrolled applied force and velocity (69). The separated device wafer20 is then cleaned (52) and mounted onto a dicing frame 25 (53).

Referring to FIG. 2A, temporary bond process B 70 a includes thefollowing steps. First, a release layer 22 is formed onto a surface 20 aof the device wafer 20 (72). The release layer is formed by firstspin-coating a precursor compound onto the wafer device surface 20 a andthen performing Plasma Enhanced Chemical Vapor deposition (PECVD) in acommercially available PECVD chamber. In one example, the precursor forthe release layer is SemicoSil™, a silicon rubber manufactured byWacker, Germany. The coated device wafer is then spin coated with anadhesive (73) and then flipped (74). Next, a soft layer 32 is spincoated on a surface 30 a of the carrier wafer 30 (76). In one example,soft layer 32 is a hot temperature cross-linking (HTC) siliconeelastomer. Next, the flipped device wafer 20 is aligned with the carrierwafer 30 so that the surface 20 a of the device wafer with the releaselayer 22 is opposite to the surface 30 a of the carrier wafer with thesoft layer 32 (77) and then the two wafers are bonded (78) in thetemporary bonder module B, shown in FIG. 2B. The temporary bond isformed under vacuum of 0.1 mbar, curing temperature between 150° C. to200° C. and low applied bond force.

Referring to FIG. 2B, the device wafer 20 is placed in the fixture chuck202 (shown in FIG. 4) with the adhesive layer facing up. Next, spacers203 are placed on top of the device wafer 20 and then the carrier wafer30 is placed on top of the spacers and the assembled fixture chuck 202is transferred to the bonder module B 310. The chamber is evacuated, thespacers 203 are removed and the carrier wafer 30 is dropped onto thedevice wafer 20. In some embodiments, the carrier wafer 30 is droppedonto the device wafer 20 by purging nitrogen or other inert gas throughvacuum grooves formed in the upper chuck 222. In other embodiments theupper chuck 222 is an electrostatic chuck (ESC) and the carrier wafer 30is dropped onto the device wafer 20 by reversing the polarity of theESC. Next, a low force is applied by purging the chamber with a lowpressure gas and the temperature is raised to 200° C. for the formationof the bond. Next, the chamber is cooled and the fixture is unloaded. Inother embodiments, the Z-axis 239 moves up and the stacked wafers 20, 30are brought into contact with the upper chuck 222. The upper chuck 222may be semi-compliant or non-compliant, as will be described later.

The debond process B 70 b is a mechanical lift debond process andincludes the following steps, shown in FIG. 2A. The bonded wafer stack10 is mounted onto a dicing frame 25 (54) and the carrier wafer 30 ismechanically lifted away from the device wafer 20 (55). The thinneddevice wafer 20 remains supported by the dicing frame 25.

Referring to FIG. 3A, temporary bond process C, 80 a includes thefollowing steps. First, a surface of the device wafer 20 is coated withan adhesive layer 23 (82). In one example, adhesive layer 23 is a UVcurable adhesive LC3200™, manufactured by 3M Company, MN, USA. Theadhesive coated device wafer is then flipped (84). Next, a lightabsorbing release layer 33 is spin coated on a surface 30 a of thecarrier wafer 30 (86). In one example, light absorbing release layer 33is a LC4000, manufactured by 3M Company, MN, USA. Next, the flippeddevice wafer 20 is aligned with the carrier wafer 30 so that the surface20 a of the device wafer with the adhesive layer 23 is opposite to thesurface 30 a of the carrier wafer 30 with the light absorbing releaselayer. The two surfaces 20 a and 30 a are brought into contact and theadhesive layer is cured with UV light (87). The two wafers are bonded(88) in temporary bonder module C 410, shown in FIG. 3B. The bond is atemporary bond between the light absorbing release layer 33 and theadhesive layer 23 and is formed under vacuum of 0.1 mbar and low appliedbond force. The temporary bonding (88) of the carrier wafer to thedevice wafer occurs in temporary module C, shown in FIG. 3B.

Referring to FIG. 3B, the carrier wafer 30 with the laser absorbingrelease layer LTHC layer is placed on the top chuck 412 and held inplace by holding pins 413. Next, the device wafer 20 is placed on thebottom chuck 414 with the adhesive layer 23 facing up. Next, the wafers20, 30 are aligned, the chamber is evacuated, and the top chuck 412 withthe carrier wafer 30 is dropped onto the device wafer 20. A low force isapplied for the formation of the bond between the release layer 33 andthe adhesive layer 23. Next, the bonded wafer stack 10 is unloaded andthe adhesive is cured with UV light.

Referring back to FIG. 3A, the debond process C 80 b includes thefollowing steps. The bonded wafer stack 10 is mounted onto a dicingframe 25 (56) and the carrier wafer 30 is illuminated with a YAG laserbeam. The laser beam causes the separation of the wafer stack along therelease layer 33 (57) and the separated carrier wafer 30 is mechanicallylifted away from the device wafer 20 (58). The adhesive layer is peeledaway from the device wafer surface 20 a (59) and the thinned devicewafer 20 remains supported by the dicing frame 25.

Referring to FIG. 5, temporary bonder cluster 110 includes a housing 101having an upper cabinet structure 102 stacked on top of a lower cabinet103. The upper cabinet 102 has a service access side 105 and the lowercabinet has leveling adjustments 104 and transport casters 106. Withinthe upper cabinet structure 102 the configurable temporary bond processmodules 210, 310, 410, 510 are vertically stacked, as shown in FIG. 6.Hot plate modules 130 and cold plate modules 140 are also verticallystacked on top, below or in-between the process modules 210, 310, asshown in FIG. 7. Additional process modules may be included in order toprovide further processing functionalities. Examples of the bond processmodules include low applied force module, high applied force module,high temperature and low temperature modules, illumination (UV light orlaser) modules, high pressure (gas) module, low (vacuum) pressure moduleand combinations thereof.

Referring to FIG. 9-FIG. 12, temporary bond module 210 includes ahousing 212 having a load door 211, an upper block assembly 220 and anopposing lower block assembly 230. The upper and lower block assemblies220, 230 are movably connected to four Z-guide posts 242. In otherembodiments, less than four or more than four Z-guide posts are used. Atelescoping curtain seal 235 is disposed between the upper and lowerblock assemblies 220, 230. A temporary bonding chamber 202 is formedbetween the upper and lower assemblies 220, 230 and the telescopingcurtain seal 235. The curtain seal 235 keeps many of the processcomponents that are outside of the temporary bonding chamber area 202insulated from the process chamber temperature, pressure, vacuum, andatmosphere. Process components outside of the chamber area 202 includeguidance posts 242, Z-axis drive 243, illumination sources, mechanicalpre-alignment arms 460 a, 460 b and wafer centering jaws 461 a, 461 b,among others. Curtain 235 also provides access to the bond chamber 202from any radial direction.

Referring to FIG. 11, the lower block assembly 230 includes a heaterplate 232 supporting the wafer 20, an insulation layer 236, a watercooled support flange 237 a transfer pin stage 238 and a Z-axis block239. Heater plate 232 is a ceramic plate and includes resistive heaterelements 233 and integrated air cooling 234. Heater elements 233 arearranged so the two different heating zones are formed. A first heatingzone 233B is configured to heat a 200 mm wafer or the center region of a300 mm wafer and a second heating zone 233A is configured to heat theperiphery of the 300 mm wafer. Heating zone 233A is controlledindependently from heating zone 233B in order to achieve thermaluniformity throughout the entire bond interface 405 and to mitigatethermal losses at the edges of the wafer stack. Heater plate 232 alsoincludes two different vacuum zones for holding wafers of 200 mm and 300mm, respectively. The water cooled thermal isolation support flange 237is separated from the heater plate by the insulation layer 236. Thetransfer pin stage 238 is arranged below the lower block assembly 230and is movable supported by the four posts 242. Transfer pin stage 238supports transfer pins 240 arranged so that they can raise or lowerdifferent size wafers. In one example, the transfer pins 240 arearranged so that they can raise or lower 200 mm and 300 mm wafers.Transfer pins 240 are straight shafts and, in some embodiments, have avacuum feed opening extending through their center, as shown in FIG. 15.Vacuum drawn through the transfer pin openings holds the supportedwafers in place onto the transfer pins during movement and preventsmisalignment of the wafers. The Z-axis block 239 includes a precisionZ-axis drive 243 with ball screw, linear cam design, a linear encoderfeedback 244 for submicron position control, and a servomotor 246 with agearbox, shown in FIG. 12.

Referring to FIG. 13, the upper block assembly 220 includes an upperceramic chuck 222, a top static chamber wall 221 against which thecurtain 235 seals with seal element 235 a, a 200 mm and a 300 mmmembrane layers 224 a, 224 b, and three metal flexure straps 226arranged circularly at 120 degrees. The membrane layers 224 a, 224 b,are clamped between the upper chuck 222 and the top housing wall 213with clamps 215 a, 215 b, respectively, and form two separate vacuumzones 223 a, 223 b designed to hold 200 mm and 300 mm wafers,respectively, as shown in FIG. 14. Membrane layers 224 a, 224 b are madeof elastomer material or metal bellows. The upper ceramic chuck 222 ishighly flat and thin. It has low mass and is semi-compliant in order toapply uniform pressure upon the wafer stack 10. The upper chuck 222 islightly pre-loaded with membrane pressure against three adjustableleveling clamp/drive assemblies 216. Clamp/drive assemblies 216 arecircularly arranged at 120 degrees. The upper chuck 222 is initiallyleveled while in contact with the lower ceramic heater plate 232, sothat it is parallel to the heater plate 232. The three metal straps 226act a flexures and provide X-Y-T (Theta) positioning with minimalZ-constraint for the upper chuck 222. The clamp/drive assemblies 216also provide a spherical Wedge Error Compensating (WEC) mechanism thatrotates and/or tilts the ceramic chuck 222 around a center pointcorresponding to the center of the supported wafer without translation.In other embodiments, the upper ceramic chuck 222 positioning isaccomplished with fixed leveling/locating pins, against which the chuck222 is lashed.

The loading and pre-alignment of the wafers is facilitated with themechanical centering device 460, shown in FIG. 16. Centering device 460includes two rotatable pre-alignment arms 460 a, 460 b and a linearlymoving alignment arm 460 c, shown in the open position in FIG. 16 and inthe closed position in FIG. 17. At the ends of each arm 460 a, 460 bthere are mechanical jaws 461 a, 461 b. The mechanical jaws 461 a, 461 bhave tapered surfaces 462 and 463 that conform to the curved edge of the300 mm wafer and 200 mm wafer, respectively, as shown in FIG. 18A andFIG. 18B. The linearly moving arm 460 c has a jaw 461 c with a taperedcurved inner surface that also conforms to the curved edge of circularwafers. Rotating arms 460 a, 460 b toward the center 465 of the supportchuck 464 and linearly moving arm 460 c toward the center 465 of thesupport chuck 464 brings the tapered surfaces of the mechanical jaws 461a, 461 b and the tapered curved inner surface of jaw 461 c in contactwith the outer perimeter of the wafer and centers the wafer on thesupport chuck 464. The three arms 460 a, 460 b, 460 c are arranged at120 degrees around the support chuck 464. In another embodiment, thecentering device 460 includes three rotatable pre-alignment arms, and atthe ends of each arm there are mechanical jaws, as shown in FIG. 18A andFIG. 18B. Rotating the arms toward the center of the support chuck 464brings the tapered surfaces of the mechanical jaws in contact with theouter perimeter of the wafer and centers the wafer on the support chuck464.

In another embodiment, the loading and pre-alignment of the wafers isfacilitated with wafer centering device 470, shown in FIG. 19A and FIG.19B. Wafer centering device 470 includes three centering linkages 471,472, 473. Centering linkage 471 includes a rectilinear mid-position airbearing or mechanical slide 471 a that moves the wafer 30 in theY-direction. Centering linkages 472, 473, include rotating centeringarms 472 a, 473 a, that rotate clockwise and counterclockwise,respectively. The motions of the centering linkages 471, 472, 473, aresynchronized by the use of a cam plate 474 with two linear cam profiles474 a, 474 b. Cam profile 474 a provides rectilinear motion for themid-position centering arm 471 and cam profile 474 b providesrectilinear motion for left and right centering arm push rods 472 b, 473b. The rectilinear motion of the push rods 472 b, 473 b, is translatedinto rotary motion at the cam/cam follower interface at the centeringarms 472 a, 473 a, respectively. The cam plate is 474 fixed to a linearslide that is driven in a rectilinear motion (X-axis motion) by anelectric motor or pneumatic actuation. A Linear Variable DifferentialTransformer (LVDT) or another electrical sensor at the mid-positioncentering arm 471 mechanism provides distance feedback, which indicatesthat the centering devices are stopped against the wafer edge. There isa spring preload on the centering device 471 a, and when the springpreload is overtaken the LVDT registers a displacement.

In yet another embodiment, the loading and pre-alignment of the wafer 30is facilitated with wafer centering device 480, shown in FIG. 19C andFIG. 19D. Wafer centering device 400 includes three centering linkages481, 482, 483. Centering linkage 481 includes a rectilinear mid-positionair bearing or mechanical slide 481 a that moves the wafer 30 in theY-direction. Centering linkages 482, 483, include rotating centeringarms 482 a, 483 a, that rotate clockwise and counterclockwise,respectively. The motions of the centering linkages 481, 482, 483, aresynchronized by the use of two plates 484, 485 that include linear camprofiles 484 a, 484 b, respectively. Cam profiles 484 a, 485 a providerectilinear motion for left and right centering arm push rods 482, 483,respectively. The rectilinear motion of the push rods 482, 483, istranslated into rotary motion at the cam/cam follower interface at thecentering arms 486 a, 486 b, respectively. Plates 484, 485 are connectedto linear slide 481 a via rods 481 a, 481 b, respectively. The linearmotion of slide 481 a in the Y direction is translated via the rods 486a, 486 b, into linear motion of plates 484, 485, respectively, along theX-axis, as shown in FIG. 19D.

Referring to FIG. 20A, FIG. 20B, FIG. 20C, the temporary bondingoperation with the bonder module 210 includes the following steps.First, the non-adhesive substrate is loaded onto the transfer pins 240 aby a robot end effector (350). In this case the substrate is a 300 mmwafer and is supported by the 300 mm pins 240 a, whereas the 200 mm pins240 b are shown to be slightly lower than the 300 mm pins 240 a. Next,the mechanical taper jaws 461 a, 461 b, move into position around thewafer and the transfer pins 240 a move down (352). The transfer pinshave vacuum and purge functions. The purge function allows the wafer tofloat during the centering cycle and the vacuum function holds the waferwhen the centering is complete. The tapered “funnel” jaws 461 a, 461 b,461 c, drive the wafer to the center as it is lowered via the transferpins 240 a. Jaws 461 a, 461 b, 461 c, are designed to accommodate andpre-align any size wafers, including 200 mm and 300 mm, shown in FIGS.19 and 18, respectively. Next, the centering jaws 461 a, 461 b, 461 cretract and the transfer pins move up to place the top substrate 20 onthe upper vacuum chuck 222, as shown in FIG. 20C (354). Next, a secondadhesive coated substrate 30 is loaded face up onto the transfer pins240 a by the robot end effector (356), shown in FIG. 21A (356). Next,the mechanical taper jaws 460 move into position around the wafer 30 andthe transfer pins 240 a move down and then up (358), shown in FIG. 21B.The centering jaws 461 a, 461 b retract and the transfer pins 240 a movedown to place the substrate 30 on the bottom vacuum chuck 232 (359),shown in FIG. 21C. Next, the lower heater stage 230 moves up to form aclose process gap between the top 20 and bottom 30 substrates and thecurtain seal 235 is closed to form the temporary bonding chamber 202(360), shown in FIG. 22A. An initial deep vacuum is drawn (10-4 mbar) inthe temporary bonding chamber 202 while the top substrate with 20 isheld via mechanical fingers. Once the set vacuum level is reached thechamber pressure is raised slightly to about 5 mbar to generate adifferential vacuum pressure that holds the top substrate 20 to theupper chuck 222. The Z-axis stage 239 moves further up to bring thebottom substrate 30 in contact with the top substrate 20, a shown inFIG. 22B (362). The top chuck 222 is lifted off from the stops 216 bythis motion (362). Next, force is applied via the top membrane 224 a andbottom top chuck 232 and the wafer stack 10 is heated to the processtemperature (364). In one example, the applied force is in the rangebetween 500 N to 8000N and the process temperature is 200 C. In caseswhere single sided heating is used, the wafer stack 10 is compressedwith the membrane pressure to ensure good thermal transfer. After theend of the treatment, the bonded wafer stack 10 is cooled and unloadedwith the help of the transfer pins and the robot end effector (366).

In the above described case, the Z-axis moves up to contact the thin,semi-compliant upper chuck 222/membrane 224 design. In this embodiment,the adhesive layer controls the TTV/tilt by applying pressure only inthe direction perpendicular to the bond interface via themembranes/chuck flexures and by using a semi compliant chuck to conformto the adhesive topography. In other embodiments, the Z-axis moves up tocontact a non-compliant chuck. In these cases the Z-axis motion controlsthe final thickness of the adhesive layer and forces the adhesive toconform to the rigid flat chuck 222. The adhesive layer thickness may becontrolled by using a Z-axis position control, pre-measured substratethicknesses and known adhesive thicknesses. In yet other embodiments, acompliant layer is installed on the bottom chuck 232 and the adhesive ispre-cured or its viscosity is adjusted. In yet other embodiments, heatis applied both through the bottom and top chucks.

Referring to FIG. 23, thermal slide debonder 150 includes a top chuckassembly 151, a bottom chuck assembly 152, a static gantry 153supporting the top chuck assembly 151, an X-axis carriage drive 154supporting the bottom chuck assembly 152, a lift pin assembly 155designed to raise and lower wafers of various diameters includingdiameters of 200 mm and 300 mm, and a base plate 163 supporting theX-axis carriage drive 154 and gantry 153.

Referring to FIG. 24, the top chuck assembly 151 includes a top supportchuck 157 bolted to gantry 153, a heater support plate 158 in contactwith the bottom surface of the top support chuck 157, a top heater 159in contact with the bottom surface of the heater plate 158, a Z-axisdrive 160 and a plate leveling system for leveling the upper waferplate/heater bottom surface 164. The plate leveling system includesthree guide shafts 162 that connect the top heater 159 to the topsupport chuck 157 and three pneumatically actuated split clamps 161. Theplate leveling system provides a spherical Wedge Error Compensating(WEC) mechanism that rotates and/or tilts the upper wafer plate 164around a center point corresponding to the center of the supported waferwithout translation. The heater 159 is a steady state heater capable toheat the supported wafer stack 10 up to 350° C. Heater 159 includes afirst heating zone configured to heat a 200 mm wafer or the centerregion of a 300 mm wafer and a second heating zone configured to heatthe periphery of the 300 mm wafer. The first and second heating zonesare controlled independently from each other in order to achieve thermaluniformity throughout the entire bond interface of the wafer stack andto mitigate thermal losses at the edges of the wafer stack. The heatersupport plate 158 is water cooled in order to provide thermal isolationand to prevent the propagation of any thermal expansion stresses thatmay be generated by the top heater 159.

Referring to FIG. 25, the bottom chuck 152 is made of a low thermal massceramic material and is designed to slide along the X-axis on top of theair bearing carriage drive 154. The carriage drive 154 is guided in thisX-axis motion by two parallel lateral carriage guidance tracks 156.Bottom chuck 152 is also designed to rotate along its Z-axis 169. AZ-axis rotation by a small angle (i.e., twisting) is used to initiatethe separation of the wafers, as will be described below. The base plate163 is vibration isolated. In one example, base plate is made ofgranite. In other examples base plate 156 has a honeycomb structure andis supported by pneumatic vibration isolators (not shown).

Referring to FIG. 26A, FIG. 26B, FIG. 26C, the debonding operation withthe thermal slide debonder 150 of FIG. 23 includes the following steps.First, the temporary bonded wafer stack 10 is loaded on the primary liftpins 155 arranged so that the carrier wafer 30 is on the top and thethinned device wafer 20 is on the bottom (171). Next, the wafer stack 10is lowered so that the bottom surface of the thinned device wafer 20 isbrought into contact with the bottom chuck 152 (172). The bottom chuck152 is then moved along the 165 a direction until it is under the topheater 159 (174). Next, the Z-axis 160 of the top chuck 151 moves downand the bottom surface 164 of the top heater 159 is brought into contactwith the top surface of the carrier wafer 30 and then air is floated ontop heater 159 and carrier wafer 30 until the carrier wafer stack 30reaches a set temperature. When the set temperature is reached, vacuumis pulled on the carrier wafer 30 so that is held by the top chuckassembly 151 and the guide shafts 162 are locked in the split clamps 162(175). At this point the top chuck 151 is rigidly held while the bottomchuck 152 is compliant and the thermal slide separation is initiated(176) by first twisting the bottom chuck 152 and then moving the X-axiscarriage 154 toward the 165 b direction away from the rigidly held topchuck assembly 151 (177). The debonded thinned device wafer 20 iscarried by the X-axis carriage 154 to the unload position where it islifted up by the pins (178) for removal (179). Next, the X-axis carriage154 moves back along direction 165 a (180). Upon reaching the positionunder the top chuck assembly 151, the lift pins 155 are raised tocontact the adhesive side of the carrier wafer 30 and air is purged ontothe heater plate 159 to release the carrier wafer from it (181). Thelift pins 155 are lowered to a height just above the bottom chuck planeso as to not contaminated the bottom chuck top surface with the adhesive(182) and the X-axis carriage 154 moves along 165 b back to the unloadposition. The carrier wafer is cooled and then removed (183).

Referring to FIG. 2A, mechanical debonder B 250 debonds the carrierwafer 30 from the thinned device wafer 20 by mechanically lifting anedge 31 of the carrier wafer 30 away from the thinned device wafer 20.Prior to the debonding process the temporary bonded wafer stack 10 isattached to a frame 25, and upon separation the thinned wafer remainssupported by the frame 25. Referring to FIG. 27 and FIG. 28, debonder250 includes a flex plate 253 with a two zone circular vacuum seal 255.Seal 255 includes two zones, one for a sealing a 200 mm wafer placedwithin the area surrounded by the seal and a second for sealing a 300 mmwafer within the area surrounded by the seal. Seal 255 is implementedeither with an O-ring or with suction cups. A lift pin assembly 254 isused to raise or lower the separated carrier wafer 30 that istransported by the flex plate 253. Debonder 250 also includes a vacuumchuck 256. Both the vacuum chuck 256 and the flex plate 253 are arrangednext to each other upon a support plate 252, which in turn is supportedby the base plate 251. Flex plate 253 has an edge 253 b connected to ahinge 263 that is driven by a hinge motor drive 257. Vacuum chuck 256 ismade of a porous sintered ceramic material and is designed to supportthe separated thin wafer 20. Hinge motor drive 257 is used to drive theflex plate 253 upon the wafer stack 10 after the wafer stack 10 has beenloaded on the vacuum chuck 256. An anti-backlash gear drive 258 is usedto prevent accidental backing of the flex plate 253. A debond drivemotor 259 is attached at the edge 251 a of the base plate 251 and nextto the edge of the chuck support plate 252 a. Debond drive motor 259moves a contact roller 260 vertical to the plane of the base plate 251in direction 261 and this motion of the contact roller 260 lifts theedge 253 a of the flex plate 253 after the flex plate has been placedupon the loaded wafer stack 10, as will be described below.

Referring to FIG. 29, the debonding operation 270 with the debonder 250includes the following steps. First, The tape frame 25 with the waferstack 10 is loaded upon the vacuum chuck 256, so that the carrier wafer30 is on the top and the thinned wafer 20 is on the bottom (271). Thetape frame 25 is indexed against the frame registration pins 262, shownin FIG. 28, and the position of the tape frame 25 is locked. Next,vacuum is pulled through the porous vacuum chuck 256 to hold the tapeframe adhesive film. Next, the hinge motor 257 is engaged to transportthe flex plate 253 onto the loaded wafer stack, so that it is in contactwith the back of the carrier wafer 30 (272). Upon reaching the positionupon the carrier wafer 30, vacuum is pulled on the carrier wafer top viathe seal 255. The torque of the hinge motor 257 is kept constant tomaintain the flex plate 253 in this “closed position”. Next, the debondmotor 259 is engaged to move the contact roller 260 up in the direction261 a and to push the edge 253 a of the flex plate 253 up (273). Thisupward motion of the flex plate edge 253 a bents (or flexes) slightlythe carrier wafer 30 and cause the wafer stack 10 to delaminate alongthe release layer 32 and thereby to separate the carrier wafer 30 fromthe thinned wafer 20. Silicon wafers break or cleave much easier alongthe (110) crystallographic plane than any other orientation. Therefore,the carrier wafer 30 is fabricated on a (110) plane so that its 110direction is perpendicular to the push direction 261 a, therebypreventing breaking of the wafer 30 during delamination. The thinnedwafer 20 remains attached to the tape frame 25, which is held by thevacuum chuck 256. Through this step the debond motor 259 is heldconstant in position. Next, the hinge motor drive 257 opens the flexplate 253 with the attached separated carrier wafer 30 in the “openposition”, in a controlled manner (274). The flex plate vacuum isreleased thereby releasing the carrier wafer 30. Next, the lift pins 254are moved up to raise the carrier wafer 30 oriented so that the releaselayer 32 is facing up and then the carrier wafer 30 is removed. Next,the vacuum through the porous vacuum chuck 256 is released and the tape25 with the attached thinned wafer 20 is removed.

Several embodiments of the present invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

1. A debonder apparatus for debonding two via an adhesive layertemporary bonded wafers, comprising: a top chuck assembly comprising aheater and a wafer holder; a bottom chuck assembly; a static gantrysupporting the top chuck assembly; an X-axis carriage drive supportingthe bottom chuck assembly; an X-axis drive control configured to drivehorizontally the bottom chuck assembly from a loading zone to a processzone under the top chuck assembly and from the process zone back to theloading zone; wherein a wafer pair comprising a carrier wafer bonded toa device wafer via an adhesive layer is placed upon said bottom chuckassembly at the loading zone oriented so that the unbonded surface ofthe device wafer is in contact with the bottom assembly and is carriedby said X-axis carriage drive to the process zone under the top chuckassembly and the unbonded surface of the carrier wafer is placed incontact with the top chuck assembly; and wherein said X-axis drivecontrol initiates horizontal motion of said X-axis carriage drive alongthe X-axis while said bonded wafer pair is heated via said heater to atemperature around or above said adhesive layer's melting point andwhile said carrier wafer is held by said top chuck assembly via saidwafer holder and said device wafer is held by said bottom assembly andthereby causes the device wafer to separate and slide away from thecarrier wafer.
 2. The debonder of claim 1 further comprising a lift pinassembly designed to raise and lower wafers placed on the bottom chuckassembly.
 3. The debonder of claim 1 further comprising a base platesupporting the X-axis carriage drive and the static gantry.
 4. Thedebonder of claim 3 wherein said base plate comprises a honeycombstructure and vibration isolation supports.
 5. The debonder of claim 3wherein said base plate comprises a granite plate.
 6. The debonder ofclaim 1 wherein said bottom chuck assembly comprises a bottom chuckcomprising a low thermal mass ceramic material and is designed to slidehorizontally along the X-axis upon said X-axis carriage drive and totwist around the Z-axis.
 7. The debonder of claim 1 wherein said X-axiscarriage drive comprises an air bearing carriage drive.
 8. The debonderof claim 1 further comprising two parallel lateral carriage guidancetracks guiding said X-axis carriage drive in its horizontal motion alongthe X-axis.
 9. The debonder of claim 1, wherein said top chuck assemblyfurther comprises: a top support chuck bolted to the static gantry; aheater support plate in contact with the bottom surface of the topsupport chuck; said heater being in contact with the bottom surface ofthe heater support plate; a top wafer plate in contact with the heater;a Z-axis drive for moving the top wafer plate in the Z-direction andplacing the top wafer plate in contact with the unbonded surface of thecarrier wafer; and a plate leveling system for leveling the top waferplate and for providing wedge error compensation of the top wafer plate.10. The debonder of claim 9 wherein said wafer holder comprises vacuumpulling said carrier wafer.
 11. The debonder of claim 9 wherein saidplate leveling system comprises three guide shafts connecting saidheater to said top support chuck and three pneumatically actuated splitclamps.
 12. The debonder of claim 9 wherein said heater comprises twoindependently controlled concentric heating zones configured to heatwafers having a diameter of 200 or 300 millimeters, respectively.
 13. Amethod for debonding two via an adhesive layer temporary bonded wafers,comprising: providing a bonder comprising a top chuck assembly, a bottomchuck assembly, a static gantry supporting the top chuck assembly, anX-axis carriage drive supporting the bottom chuck assembly and an X-axisdrive control configured to drive horizontally the X-axis carriage driveand the bottom chuck assembly from a loading zone to a process zoneunder the top chuck assembly and from the process zone back to theloading zone; loading a wafer pair comprising a carrier wafer bonded toa device wafer via an adhesive layer upon said bottom chuck assembly atthe loading zone oriented so that the unbonded surface of the devicewafer is in contact with the bottom assembly; driving said X-axiscarriage drive and said bottom chuck assembly to the process zone underthe top chuck assembly; placing the unbonded surface of the carrierwafer in contact with the top chuck assembly and holding said carrierwafer by said top chuck assembly; heating said carrier wafer with aheater comprised in said top chuck assembly to a temperature around orabove said adhesive layer's melting point; initiating horizontal motionof said X-axis carriage drive along the X-axis by said X-axis drivecontrol while heat is applied to said carrier wafer and while saidcarrier wafer is held by said top chuck assembly and said device waferis held by said bottom chuck assembly and thereby causing the devicewafer to separate and slide away from the carrier wafer.
 14. The methodof claim 13 further comprising raising and lowering said wafer pair ontothe bottom chuck assembly via a lift pin assembly.
 15. The method ofclaim 13 wherein said bonder further comprises a base plate supportingthe X-axis carriage drive and the static gantry.
 16. The method of claim15 wherein said base plate comprises a honeycomb structure and vibrationisolation supports.
 17. The method of claim 15 wherein said base platecomprises a granite plate.
 18. The method of claim 13 further comprisingtwisting the device wafer at the same time said horizontal motion isinitiated.
 19. The method of claim 13 wherein said X-axis carriage drivecomprises an air bearing carriage drive.
 20. The method of claim 13wherein said debonder further comprises two parallel lateral carriageguidance tracks guiding said X-axis carriage drive in its horizontalmotion along the X-axis.
 21. The method of claim 13, wherein said topchuck assembly further comprises: a top support chuck bolted to thestatic gantry; a heater support plate in contact with the bottom surfaceof the top support chuck; said heater being in contact with the bottomsurface of the heater support plate; a top wafer plate in contact withthe heater; a Z-axis drive for moving the top wafer plate in theZ-direction and placing the top wafer plate in contact with the unbondedsurface of the carrier wafer; and a plate leveling system for levelingthe top wafer plate and for providing wedge error compensation of thetop wafer plate.
 22. The method of claim 13 wherein said carrier waferis held by said top chuck assembly via vacuum pulling.
 23. The method ofclaim 13, wherein said plate leveling system comprises three guideshafts connecting said heater to said top support chuck and threepneumatically actuated split clamps.
 24. The method of claim 13, whereinsaid heater comprises two independently controlled concentric heatingzones configured to heat wafers having a diameter of 200 or 300millimeters, respectively.